Apparatuses for methods for operation of three-phase rotating electrical machines are increasingly required and are being used increasingly nowadays. One suitable apparatus, for example, is disclosed in EP 1 521 356 A2, which specifies a rotating electrical machine which has two stator winding sets. Furthermore, an associated converter unit is in each case provided to feed each stator winding set. A respectively associated regulation device is provided for each of the converter units, in order to drive the associated converter unit by means of a drive signal. Furthermore, measurement means are provided for measurement of the currents in a stator winding set, which measured currents are supplied to the associated regulation device, with this regulation device acting as a so-called “master”, that is to say the measured currents of the “master” regulation device, of the other regulation device, which acts as a so-called “follower”. The preset, that is to say the measured currents, is provided via a data line. In response to the currents predetermined by the “master” regulation device, the “follower” regulation device then emits an appropriate drive signal to its associated converter device, that is to say the drive signal of the “follower” regulation device is dependent on the preset from the “master” regulation device, with this preset representing a reference.
EP 1 732 204 A1 specifies a method for operation of a rotating electrical machine, in which method the respective stator winding set is fed by the associated converter unit. In order to allow redundant and independent regulation or in order to influence electrical variables of the individual stator winding sets of the rotating electrical machine, the currents are measured in at least n−1 phase windings of each stator winding set. A respectively associated regulation device is provided for each converter unit, and each converter unit is driven by means of a drive signal from the associated regulation device, independently of the regulation devices for each of the other converter units. Furthermore, the drive signal in the respective regulation device is formed from the measured currents in each stator winding set.
Furthermore, the two stator winding sets of the rotating electrical machine in EP 1 521 356 A1 and in EP 1 732 204 A1 are typically each connected in star, with the star circuits of the stator winding sets having a phase shift of 30 degrees electrical with respect to one another (referred to as: YY30). One undesirable phenomenon of such rotating electrical machines is that, in particular, fifth and seventh stator current harmonics with respect to the stator current fundamental, but in general the k-th stator current harmonics with respect to the stator current harmonic occur in both stator winding sets, where k=6n+/−1 and n=1, 3, 5, . . . . These stator current harmonics have a negative effect and are therefore unacceptable.